MathDB
line from arc midpoint perpendicular to a side

Source: Sharygin Geometry Olympiad 2016 Final Round problem 2 grade 8

July 22, 2018
geometryarc midpointcircumcircleperpendicularparallelogram

Problem Statement

A circumcircle of triangle ABCABC meets the sides ADAD and CDCD of a parallelogram ABCDABCD at points KK and LL respectively. Let MM be the midpoint of arc KLKL not containing BB. Prove that DMACDM \perp AC.
by E.Bakaev